Family
by Shadow On The Full Moon
Summary: {Undertale (c) Toby Fox} He knew Sans treasured every moment they spent in the lab working together. And even though he heard his brother scream, a look of horror on his face as tears streamed down his face as the machine malfunctioned, he couldn't bring himself to regret letting Sans stay. Rated T.


**Undertale © Toby Fox**

 **Story © Me**

 **Notes- Wanted to write a little one-shot with Gaster, Papyrus, and Sans. Enjoy.**

~*~*~ Brothers~*~*~

{Sans? Papyrus? I'm home!} Gaster called as he walked in to the house. He listened, for the sound of the younger twins, for a minute. He finally heard giggles from the two from behind the couch.

{..Huh. I wonder my little brothers could be… } he said tapping his chin, hearing more muffled giggles. He set his bag down walking in front of the couch. He caught a glimpse of Sans' blue over sized jack fluff sticking out, from the side. He grinned and walked to the stairs. {maybe they are up stairs.} He walked in place letting his footsteps get quieter using his magic to open a door and close it. The twins popped out giggling as he snuck over he snatched the 14 year olds up making them yelp and laugh.

{Gotcha!} he said, chuckling as they laughed. He set them down on the couch sitting down next to them.

"haha, how was work, bro?" sans asked, grinning.

{It was fine, how was your day?} Gaster asked is siblings.

"IT WAS FUN! SANS AND I PLAYED WITH SOME OF THE OTHER KIDS!" Papyrus said. Sans nodded in agreement.

"yeah, it was… _bone_ -rific." Sans snickering. Papyrus groaned and face planted into the couch arm as Gaster shook his head, smiling some.

{That's good to hear.} he said.

"so discover anything new?" sans asked excitedly. Gaster shook his head.

{Nope, sorry, Kiddo. But when I do, you'll be the first one I tell.} he said. Sans smiled more. Like him, the shorter twin had a passion for science, and would often run into Gaster's lab that he had at home to watch him work. Gaster loved his brothers and loved that Sans was so interested in science, (if the Quantum Physics books inside the joke books didn't tell him it was certainly Sans constant questions about his job and the lab) and loved how energetic Papyrus was. That's why he never had the heart to tell them about the timelines.

He listened as Sans told another pun and watched as Papyrus tackled him of the couch. He smiled as he watched the two roll around, Sans laughing which made Papyrus laugh as well as they continued to 'fight'.

~*~*~A few years later~*~*~

Sans and Papyrus were young adults and Sans had somehow managed to land a job as Gaster's assistant. Papyrus had landed himself in training to become a royal guard. Gaster had been shocked when Sans walked in with Asgore, and introduced as his new assistant. Sans had ran up to him asking what they would be working on first. Asgore had left them as Gaster explained what they would be working on. Sans was looking around the lab looking like a 5 year old in a candy shop. That was when he found Gaster's notes about the timeline repeating and the messing of time. Sans had gone silent as he had been talking happily cracking science jokes and puns. So when the lab went silent, Gaster turned to see what his brother had gotten distracted by. Sans looked up at Gaster gripping the papers.

"…you… You noticed it too." He said, voice quiet, lights in his eyes dimming. Gaster went over taking his notes and set them down.

{You know about it?} he asked just as quiet.

"…Yes. I…Thought that it was just me. Why didn't you say anything?" Sans asked.

{…I didn't think anyone noticed. That and I did not want to worry you or Papyrus.} the elder said.

"Maybe we can see what's causing it." Sans said turning to his bag and digging into it pulling out a beaten up notebook. "..I've been tracking it. I've even did some research into it." Sans continued handed Gaster the book. The scientist flipped through the pages carefully, reading over the detailed notes and questions and theories. He got to one page of a detained sketch of a machine.

{What is this?} he asked looking at his brother, who gave a sheepish grin shrugging.

"Time machine… of sorts…" he answered. Gaster studied the blue print, he flipped to the next page filled with more notes and even more questions and theories. Another page, another sketch of a machine, a small one this time with notes, and the sketch seemed unfinished.

{And this?} he asked.

"A device to monitor the disruptions of time.. Work in progress." Sans said.

{Haha, sorry to break it to you, brother, but it seems I beat you to that one.} Gaster said turning the page before closing the book and handing it to Sans.

"…you… you made the one?" he asked. "Can I see it?" he asked, the lights in his eyes brightening in excitement.

{Later, after we finish today's work.} Gaster said. Sans nodded.

Gaster smiled as they started to work, he was sad that Sans had to pick up on it and get involved, but at the same time, he felt pride that his younger brother had become so observant.

~*~*~He shouldn't have allowed Sans to work with him~*~*~

Months passed as they worked on the machine and observed time, half way through Alphys, a young scientist, joined them in their work. They didn't inform her about the real reason, she didn't ask. The three worked together becoming friends quickly, and joking around the lab as they worked. Sans being the one joking around mostly, Gaster every once in a while throwing a pun back at him making his brother laugh.

Gaster enjoyed every second of it, he enjoyed his work even more with Sans at his side working and questioning everything never satisfied with an answer until he deemed it perfect and acceptable, loved it when he would find sans napping in his own work space mumbling about whatever they had been working on that day and waking up and immediately getting to work. He enjoyed having the shy young assistant Alphys around and talking with her as well as helping her when she came to him with blue prints of a robot she was building for a friend of hers.

He enjoyed working on the machine with them. Enjoyed the way Sans eyes sparkled as they got closer to finishing the machine. How Alphys smiled and relaxed and became just as talkative.

Most of all, he enjoyed leaving the Lab, Sans at his side talking excitedly about the findings of the day or about their project. He loved arriving home and hearing about Papyrus' day, and him talking about how Awesome Undyne was and how training was going great. Gaster loved listening to Sans making a pun and Papyrus yelling at him, while Sans just grinned and poked at him more until the two were on the floor rolling around. It was strange, and funny seeing at Papyrus was about Gaster's height with Sans coming up a little lower than half of their ribs.

Gaster smiled, the one thing he loved was his family. He would watch as they break apart, Sans laughing too hard to move as Papyrus started to laugh as well. Sometimes he would join in the scuffle making his brothers yelp and laugh.

He knew that Papyrus and Sans loved it as well. He knew Sans treasured every moment they spent in the lab working together. And even though he heard his brother, scream a look of horror on his face as tears streamed down his face as the machine malfunctioned, he couldn't bring himself to regret letting Sans stay.

Sans screamed fighting his Brother's magic, clawing at the air as he struggled as Gaster was yanked into the machine. Alphys had dived for cover taking the skeleton with her as there was a flash filled the room, Sans Screaming for his elder brother sobbing as he struggled in his friends grip. He got free as the flash faded and the room cleared, he gaze on the broken machine. Sans choked on a sob scrambling to the machine and messing with it.

"No, no, no, no, no, no, no, no, no, NO!" he cried, punching the machine, he looked around frantically yelling for his brother as Alphys sat in a dazed shock. "Gaster! Gaster, please! COME OUT! PLEASE! YOU CAN'T BE DEAD! GASTER!" Sans screamed as he collapsed to his knees sobbing. He heard Alphys crawling towards him and hugging him as she snapped out of her daze, he clung to her as he sobbed. After hours of sobbing, Sans had managed to stand, dragging himself to the machine, walking around it preparing it for transport. Once he was packed he and Alphys went to the king. That's when they found out that not only had Gaster been killed, he'd been erased. No one remembered or knew who the Royal Scientist had been. Asgore asked if they come to apply. Sans turned down the offer but gave Alphys a nod letting her know that she should take the opportunity.

Sans left, not having the heart to return to his twin, or return to the house knowing that Gaster wouldn't be returning with him. He found himself in Snowdin and in front of a house for sell. He went inside looking around. At the back was a small space, perfect for a small lab. Soon, Sans found him placing the machine in the room and leaving locking the door before standing in front of his current home. He blinked, confused but brushed it off as him zoning out. He went inside and called out for his twin. Papyrus come out of the kitchen and grinned at him, he asked how Sans day was, freaked out as Sans nearly broke down, but never once did he ask about Gaster. He told Papyrus he was fine, that it was a long day. Then he told him about the nice cozy cabin he'd found in Snowdin.

A few days later they're moved in and comfy. Sans started working on the machine, for a while the problems with time stopped. Years passes, Sans and Papyrus became sentries, during one of his breaks Sans met the lady behind the door and they talked. Telling jokes back and forth.

He made a promise to protect any human.

Then Frisk walked through the door.

And then the RESETs started again

Sans kept track of them, making notes, and working on the machine, all the while watching the human.

When the Barrier was finally broken and they all stood looking out towards the city, Frisk trembling slightly next to him in near tears, all he could think was how much he wished that Gaster could see this. He side glanced as Alphys who was glancing at him. She gave a sad smile and a small nod. Sans smiled nodded back and looked ahead.

The months passed, and Sans finally finished the machine. At his side stood, Frisk and Alphys. Behind them, were the others. Sans had hesitated before switching on the machine. He closed his eyes, waiting to be jerked in, and the screams of Frisk and Papyrus as he was ripped apart. Instead of screams and the sound of sobbing and struggling, he heard gasps. He opened his eyes and looked up and choked back a sob as he stared up at Gaster. The ex-royal scientist had cracks in his skull, one trailing up from his right eye socket, and the other going down from his left.

"G-Gaster…" he choked out. The elder skeleton looked at him and gave a small smile. Sans threw himself at his brother who hugged him tightly, soon after Papyrus threw himself into the hug as well.

Gaster blinked as he was suddenly in one piece. He heard a choked call of his name and looked over seeing Sans in near tears as he stared at him, behind him Papyrus was also at the point of tears. He gave a small smile, and Sans threw himself into his arms. He hugged him back and looked up at Papyrus holding out one of his arms keeping the other wrapped tightly as Sans. The taller twin rushed over hugging him, Gaster wrapped the arm around him clinging to his younger brothers. They sank to the floor, Gaster smiling as he held his brothers rubbing Sans back as the shorter twin sobbed into his shoulder.

{Shhh, it's alright.} he said.

"I-it's great to have you back, D-dr. Gaster." Alphys said.

{It's great to be back.} Gaster said. Sans pulled away wiping his eyes as Papyrus did the same. Sans smiled.

"I… I thought that it wouldn't work." He said. Gaster looked at the machine.

{But it did. Thank you, Sans. You are a true scientist.} Gaster said. Sans smiled more at the praise. Asgore stepped forward.

"It's strange, seeing you after all this time." he said.

{It is strange being whole again… I was scattered for so long… I'm surprised I can even talk… let alone move.} Gaster said. {…Tell me, what is this?} the question was directed as Sans as the three skeletons stood.

"we're on the surface. it's a good one, we're free… it… took a lot of tries… but… we're free." Sans answered then looked behind him to motion someone over. He glanced up to see a human slowly walking over to Sans' side. Gaster blinked. The human smiled at him.

"It's great to meet you. Sans told me a lot about you. I'm Frisk." they said. Sans smiled and looked up as him

"Frisk was the one who freed us." He said.

{Well, Frisk, it is a pleasure to meet you.} he said holding out his hand. Frisk took it and they shook.

"Why don't we move the reunion party into the house?" Undyne ask coming up putting an around Alphys. Sans nodded in agreement.

"I'll make some spaghetti!" Papyrus said rushing out of the house. Undyne immediately followed.

"someone should make sure they don't destroy the kitchen." Sans said. There was an explosion of some sorts and Undyne yelling. Alphys, Toriel, and Asgore ran out and into the house. Sans chuckled and put an arm around Frisk and they walked after the three. Gaster followed slowly smiling as Sans turned back to him and grinned.

As they left the lab and went inside, Sans called out a pun. Papyrus' enraged yell echoed from the kitchen followed by Undyne ordering Sans to keep making them which he happily did. Toriel joined in at one point Asgore and Alphys shook their heads, as Frisk laughed. Papyrus suddenly tackled Sans who burst into laughter as they rolled. They broke apart in fits of giggles and laughter, as the other laughed with them.

Gaster smiled as he looked around the room, and once again found himself once again, not regretting a thing.

~*~*~End~*~*~

 **I hope you guys enjoyed that. I may write more of Gaster in the future, I'm not sure.**

 **~Shadow On The Full Moon**


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